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Oceans swallowed 13 million tonnes of plastic in 2010

Vast floating islands of plastic are just a drop in the ocean compared with what’s lurking deeper down. Between 5 and 13 million tonnes of plastic debris entered the marine environment in 2010 – and most of it is under water. What’s more, without improvements in the way we manage waste, it could be 10 times as much each year by 2025.

The visible plastic is just a small proportion of what's in the oceans <i>(Image: Pascal Kobeh/Naturepl.com)</i>

It has been 40 years since the first scientific reports of plastic pollution in the ocean, but we still have plenty to learn. For instance, the combined results from 24 oceanic expeditions published late last year concluded there may beperhaps 244,000 tonnes of floating plastic out there. This is puzzling, because conservative estimates suggest something like 9 million tonnes of plastic have entered the oceans since the 1970s.

Now we know there’s even more missing plastic than that. Jenna Jambeck at the University of Georgia, Athens, and her colleagues have looked at data on plastic use and disposal in 192 coastal countries. They calculate that between 4.8 and 12.7 million tonnes entered the world’s oceans in 2010 alone. This means the amount of plastic that has entered the ocean down the years might be 1000 times more than the mass of floating plastic that scientific surveys have measured.

Surprisingly, the 10 countries with the largest problem – many of which are in south-east Asia – generally have relatively low rates of plastic waste generation per person. For instance, in China – which tops the list with an estimate of up to 3.53 million tonnes of plastic marine debris a year – the average person generates about 1.1 kilograms of waste per day of which just 11 per cent is plastic. In the US – at 20 on the list – the average person generates more than twice as much waste. But the top offending countries also have high coastal populations and low rates of plastic recycling.

It’s an interesting study, says Marcus Eriksen of the Five Gyres Institute in Los Angeles, who led last year’s floating plastic study

– but some of the assumptions used to arrive at the new calculations could be quibbled with. “I believe the authors underestimate the amount of trash that is scavenged, burned and buried before it reaches the ocean,” he says. “I think there’s much less leaving land.”

Even so, there is clearly a huge mismatch between the plastic entering the ocean and the plastic we find there. “The disturbing conclusion is that much of the plastic entering the oceans is unaccounted for,” says Carlos Duarte at the King Abdullah University of Science and Technology in Saudi Arabia, who has also helped conduct surveys into the amount of plastic in the oceans.

Plastic smog

Where is the missing plastic? Perhaps it’s hiding in plain sight. “It’s important to understand that plastic shreds rapidly into microplastics that distribute widely into the most remote waters on the planet,” says Eriksen. “Of the 5.25 trillion particles of plastic we reported recently in PLoS One, 92 per cent are less than the size of a grain of rice.”

Such small particles spread throughout the water column, says Eriksen, also finding their way into sea-floor sediments and ice cores. That means we should stop thinking of plastic waste in terms of unsightly chunks of debris floating in vast oceanic garbage patches, and instead see it more as a pervasive “plastic smog” of tiny particles spread through the entire volume of ocean water.

“It’s not sensible to go to the ocean with nets to capture trash, but rather to focus on mitigation strategies on land,” says Eriksen.

Yet the amount of plastic entering the ocean is likely to keep rising in the years to come. Jambeck and her colleagues point out that 16 of the top 20 plastic producers they identified are middle-income countries, where strong economic growth will probably result in even more plastic use, but where the infrastructure to deal with the waste is still lacking.

But the solution isn’t to burden these developing countries with the cost of building effective waste management infrastructures, says Eriksen. Instead, we should require the plastics industry to rethink the way it designs its products – in particular, the industry should phase out plastic products designed for single use.

Change the way plastic is produced, says Eriksen, “and the plastic pollution issue would largely diminish”.

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Suicide accounts for more than 40,000 deaths in the US each year, making it one of the top 10 leading causes of death in the country. While psychological factors such as stress, anxiety and depression are known drivers of suicide, a new study claims to have found evidence of a more surprising risk factor: exposure to air pollution.

The researchers, including Amanda Bakian, PhD, an assistant professor of psychiatry at the University of Utah in Salt Lake City, publish their findings in The American Journal of Epidemiology.

Smog over a city

This is not the first study to find a link between air pollution and increased risk of suicide. A 2010 studypublished in The American Journal of Psychiatry found people from over seven cities in South Korea were 9% more likely to commit suicide within 2 days of a rise in air pollution.

And last year, Bakian and colleagues conducted a study that found residents of Salt Lake County were more likely to commit suicide within 3 days of being exposed to increased levels of nitrogen oxide or high concentrations of fine particulate matter (PM 2.5) – particles in smoke and haze that are 2.5 micrometers in diameter or less.

They build on these findings with their latest study, which found middle-aged individuals and men are most at risk of suicide through exposure to air pollution.

Short-term air pollution exposure ‘increased suicide risk by up to 25%’

The team analyzed the records of 1,546 people in Salt Lake County who committed suicide between 2000 and 2010.

Consistent with their previous findings, the researchers calculated that individuals who were exposed to increased levels of nitrogen dioxide were 20% more likely to commit suicide in the following 3 days, while those exposed to higher concentrations of PM 2.5 were 5% more likely to take their own lives within the next 3 days.

Men were found to have an even higher risk of suicide following air pollution exposure; after exposure to increased levels of nitrogen dioxide and PM 2.5, their risk of committing suicide in the following 3 days was 25% and 5%, respectively.

For individuals aged 36-64, the researchers found that short-term exposure to high levels of nitrogen dioxide increased the risk of suicide by 20%, while short-term exposure to high concentrations of PM 2.5 was linked to a 7% increased suicide risk.

Commenting on their findings, Bakian says:

“As suicide risk was found to differ by age and gender, this suggests that vulnerability to suicide following air pollution exposure is not uniform across Salt Lake County residents and that some Salt Lake County residents are more vulnerable than others.

Our next step is to determine in more detail exactly what elements – such as genetic and sociodemographic factors – are responsible for increasing one’s vulnerability to suicide following air pollution exposure.”

The researchers stress that their findings do not indicate that short-term exposure to air pollution is a direct cause of suicide. Instead, they suggest that increased air pollution may merge with other factors that drive suicide risk.


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A new study published in the New England Journal of Medicine suggests current estimates about the number of Americans who die from cigarette smoking are too low.

The American Cancer Society (ACS) funded study suggests estimates from the Surgeon General that show smoking kills about 480,000 people in the US every year, exclude tens of thousands of Americans who die from diseases not counted as caused by smoking but perhaps should be.

close up person smoking

For their analysis, Dr. Eric J. Jacobs, strategic director of Pharmacoepidemiology at the ACS, and colleagues reviewed data from 5 large studies, including the ACSCancer Prevention Study-II, the Health Professionals Follow-up Study, the Nurses’ Health Study, and the National Institutes of Health AARP Diet and Health Study.

The data covers nearly a million Americans aged 55 and over that were followed for about 10 years, during which time there were over 180,000 deaths, including nearly 16,500 among current smokers.

As expected, the analysis showed current smokers were nearly three times more likely to die in that time than people who never smoked.

Most of the excess deaths in smokers were due to diseases that are known to be caused by smoking. These include 12 types of cancer, stroke, coronary heart disease and chronic obstructive pulmonary disease (COPD – which includes chronic bronchitis, emphysema and chronic obstructive airways disease).

Smokers had double risk of death from diseases not classed as caused by smoking

However, Dr. Jacobs and colleagues also found that around 17% of the excess deaths in current smokers were attributed to diseases outside of the list of 21 that the US Surgeon General classes as caused by smoking and so are excluded in official estimated US deaths due to tobacco use.

Fast facts about smoking

  • Tobacco use is the leading preventable cause of death worldwide
  • Smoking and tobacco use costs the US $289 billion a year, including more than $156 billion in lost productivity
  • In 2011, the tobacco industry spent nearly $23 million a day on promoting and advertising cigarettes.

Find out why smoking is bad for you

The investigators drew particular attention to where they found a double risk of death among current smokers due to diseases such as intestinal ischemia (narrow or blocked arteries in the gut), kidney failure, infections, hypertensive heart disease and various types of respiratory disorders outside of COPD.

The authors note that even though these diseases are not officially regarded as being a result of smoking, and are therefore excluded from estimates of smoking-related deaths, there is strong evidence to suggest they are.

Their analysis also showed that excess risk of death from each of these conditions fell when participants gave up smoking.

The team found smoking was also tied to smaller increases in risk of death from breast cancer, prostate cancer and cancers of unknown sites. These diseases are currently not formally classed as being caused by smoking.

The authors conclude that the number of additional deaths potentially linked to smoking is significant and may be due to diseases not formally established as caused by smoking. However, should future research show they are, then they should be included in estimates of the death toll from tobacco use.

The study only covered data on one million people taking part in large studies, but Dr. Jacobs says:

“If the same is true nationwide, then cigarette smoking may be killing about 60,000 more Americans each year than previously estimated, a number greater than the total number who die each year ofinfluenza or liver disease.”


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Woman Becomes Obese After Fecal Transplant From Overweight Donor

While they may sound totally disgusting, fecal transplants are emerging as a promising treatment for a variety of gastrointestinal diseases, in particular infection with the bacteriaClostridium difficile. They don’t quite involve directly inserting the feces of one person into another, but rather the donor stool is rinsed and strained and then introduced into the recipient, either through an enema or endoscopy, or orally in pill form. The idea is to replace healthy bacteria in the gut after the normal balance is disturbed, for example by antibiotics.

One woman suffering recurrent C. difficile infection was recently successfully treated with this procedure, but interestingly, she also rapidly went from normal weight to becoming obese after receiving the transplant. While the weight gain could be due to a variety of factors, the donor was also overweight, and the recipient had never struggled with her weight before. Researchers are therefore speculating whether something in the transplant could have played a role in her weight gain, and have described the intriguing case in Open Forum Infectious Diseases.

The individual described in the report was a 32-year-old female who presented with recurrent C. difficile infection. This bacterium commonly affects those treated with antibiotics and can cause a variety of unpleasant symptoms, ranging from diarrhea and abdominal cramps to life-threatening complications such as severe bowel swelling.

Alongside testing positive for this particular bacterium, examination revealed that she was also infected with another species called Helicobacter pylori, a common bacterium that can also cause similar symptoms to C. difficile infection. The woman was therefore prescribed a cocktail of antibiotics, but her symptoms recurred after she completed the course. She was then put on different antibiotics, but the same thing happened again. The woman therefore decided to give fecal transplant a go, electing her daughter as the donor.

At the time, the woman was a healthy 136 pounds with a normal BMI of 26. Her daughter weighed 140 pounds at the time, with a BMI of 26.6, but became overweight shortly afterward. Following the therapy, the woman’s symptoms vanished and she no longer experienced recurrent infections.

Sixteen months later, however, the woman reported unintentional weight gain of 34 pounds and met the criteria for obesity. Two and a half years after the transplant, the woman weighed 177 pounds with a BMI of 34.5, despite a medically supervised liquid protein diet and exercise program.

“We’re questioning whether there was something in the fecal transplant, whether some of those ‘good’ bacteria we transferred may have an impact on her metabolism in a negative way,” case report author Colleen Kelly said in a statement.

This would not be the first time that an association between gut bacteria and weight has been reported. Several animal studies have shown that fecal transplant from an obese mouse into a normal-weight mouse can cause a significant increase in fat. However, there are also several other possible factors which could explain her weight gain, for example an increase in appetite following resolution of the infection. Furthermore, links between H. pylori treatment and weight gain have also previously been demonstrated. But given the fact that both the daughter and the mother gained weight, the researchers conclude that the transplant was at least partly responsible for the obesity.


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Type 1 Diabetes Linked To Decreased Diversity In Microbiome

Type 1 diabetes, also known as juvenile diabetes, is a disease in which the body does not produce enough insulin to process glucose in the blood. A new study, the largest of its kind, published by Cell, Host & Microbe explores the relationship between decreased genetic diversity of gut microbes and the onset of type 1 diabetes. This could lead to the development of new therapies. Aleksandar Kostic from the Broad Institute of MIT and Harvard was lead author on the paper, and the work was funded by the Juvenile Diabetes Research Foundation (JDRF).

The human body contains about 100 trillion microbial cells, ten times as many as human cells. This microbiota is essential for proper digestion, skin health, vaginal health, and a number of other things. When the balance of these microbes gets out of whack, health issues can set in. Though prior work has indicated a link between microbiota and one’s predisposition to type 1 diabetes, the current research has reinforced that association.

“We know from previous human studies that changes in gut bacterial composition correlate with the early development of type 1 diabetes, and that the interactions between bacterial networks may be a contributing factor in why some people at risk for the disease develop type 1 diabetes and others don’t,” Jessica Dunne from JDRF said in a press release. “This is the first study to show how specific changes in the microbiome are affecting the progression to symptomatic T1D.”

The study focused on 33 infants with a genetic predisposition to developing type 1 diabetes, monitoring stool samples over the course of three years. These stool samples were tested, giving them an indication of the diversity and health of the individual’s microbiota. A few of the infants being followed were diagnosed with type 1 diabetes during the study.

“This study is unique because we have taken a cohort of children at high risk of developing type 1 diabetes and then followed what changes in the microbiome tip the balance toward progression to the disease,” added senior author Ramnik Xavier.

On average, the diversity of their respective microbiomes was reduced by about 25% when compared to the healthy children who did not develop the disease. On top of merely serving as a control, the children who did not develop type 1 diabetes served as a fantastic resource for learning about how the microbiome develops in early childhood, and how it is maintained over time.

“Whether the bacterial community is very small, as it is in early infancy, or if it’s larger as it is later in life, the community is always serving the same major functions regardless of its composition. No matter which species are present, they encode the same major metabolic pathways, indicating that they’re doing the same jobs,” Kostic explained.

Moving forward, the researchers would like to follow infants genetically predisposed to type 1 diabetes from different regions. The children studied in this paper were all from Finland and Estonia. Analyzing children from different regions could help account for geographical and regional dietary factors which may not have influenced this study.


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The Moon Was A First Step, Mars Will Test Our Capabilities, But Europa Is The Prize

The icy moon Europa is perhaps the most tantalising destination in our solar system. Scientists have been trying for years to kickstart a mission to Jupiter’s most enigmatic moon, with very Earth-like concerns over costs keeping missions grounded until now.

The European Space Agency’s ambitious mission to Jupiter, JUICE, will visit its fire-and-ice moons – volcanic Io, icy Europa, giant Ganymede, and cratered Callisto – in the 2030s. But it will only provide a glimpse of Europa’s surface from a couple of close flybys. With the announcement of the NASA-led Europa Clipper mission, now it looks like a much closer inspection of Europa is on the cards.

It’s hard to overstate the excitement among planetary scientists, after so many years of waiting in the wings while all eyes were on Mars. This is truly a quest to understand what makes a world habitable.

A Watery World

Europa is the smallest and smoothest of the four Galilean moons. At 1,940 miles across, it is roughly a quarter of the size of Earth, composed of a mixture of ices and rocks. When the Galileo spacecraft flew over Europa in the 1990s, it uncovered evidence of a global sub-surface ocean: vast, deep, dark waters hidden beneath the ice crust.

The water doesn’t freeze completely because it’s constantly kneaded by powerful tidal forces as the moon orbits around Jupiter once every 3.5 days. What’s more, the ocean is believed to be in direct contact with the surface ices and the moon’s silicate mantle, which brings together all the necessary ingredients for a habitable environment: liquid water, a source of energy, and a source of minerals/nutrients. We know that life on Earth can exist in even the most extreme environmental conditions (for example, bacteria known asextremophiles), so maybe – just maybe – Europa’s hidden ocean could support life.

The Galilean moons of Jupiter: Io, Europa, Ganymede and Callisto. NASA

What To Look For

Neither JUICE nor Clipper will reach the surface or the ocean below – that’s too great a technological challenge for now. But if habitable conditions for life are discovered beyond Earth, particularly somewhere as far from the Sun as Jupiter and its moons, this could mean that habitable conditions are commonplace throughout our universe.

We must begin to explore Europa via orbital reconnaissance: to image and perform spectral analysis of the composition and geology of the surface, and the radiation, magnetic, electric and plasma fields that sweep across it. With ice penetrating radar we can probe through the icy crust, even as far as the hidden ocean to understand the forces that shape this icy world.

Europa’s ‘chaos terrain’, caused by repeated freezing and melting. NASA

Europa’s fractured and cracked surface is geologically quite young, and relatively crater-free. The structures that the Galileo probe observed from orbit suggest freeze-melt processes that trap icy burgs into frozen seas, creating the scarred patterns known aschaos terrain. Dark parallel ridges criss-cross the bright planes, possibly due to tectonics or other geologic processes.

Most surprising was Hubble’s observations in 2012, which showed evidence of huge plumes or geysers erupting tens of kilometres over Europa’s south pole, potentially contributing to a very thin atmosphere. If we could directly sample those plumes we might just get a glimpse of the composition of the deep ocean.

Sooner Rather Than Later

So for all these reasons and more, Europa remains the highest priority target for a future mission. That there are two missions to the Jupiter system stems from years of study within NASA and ESA. At one point a joint mission, the Europa-Jupiter System Mission, was planned but was not taken forward due to funding constraints.

The Jupiter Icy Moon Explorer, JUICE, and its instruments. ESA

Today, JUICE is full-steam ahead, the project having passed through a full study and definition phase towards now building the spacecraft. If all goes to plan it would launch in 2022 and reach Jupiter in 2030. After two years of multiple fly-bys exploring Jupiter, its moons, rings and magnetosphere, it will become humankind’s first orbiter of an icy moon, targeting Ganymede in late 2032. If NASA’s recently announced funding is confirmed Europa Clipper may proceed even faster, using a new rocket (the Space Launch System) to propel it towards Europa in only a few years, potentially arriving just before or even at the same time as JUICE.

Clipper will conduct multiple flybys of Europa (maybe 45 or more over three years) without entering orbit directly, but will provide the high-resolution reconnaissance necessary to ultimately choose a landing site for some future robotic explorer. Although that future landing mission is beyond the funding horizon right now, it’s exciting to think that we’ll one day see images from that icy and harsh environment, with Jupiter suspended in the black skies above.